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An organism is defined in a medical dictionary as any living thing that functions as an individual. [1] Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism.
v. t. e. A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells . The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India.
A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. [1] All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium.
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. Most prokaryotes are unicellular and are classified into bacteria and archaea.
A colony of Escherichia coli [111] Unlike in multicellular organisms, increases in cell size ( cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. [112]
Eukaryotes are organisms that range from microscopic single cells, such as picozoans under 3 micrometres across, [7] to animals like the blue whale, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long, [8] or plants like the coast redwood, up to 120 metres (390 ft) tall. [9]
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations.
This organism is estimated to be 2,400 years old. The fungus was written about in the April 2003 issue of the Canadian Journal of Forest Research. If this colony is considered a single organism, then it is the largest known organism in the world by area, and rivals the aspen grove "Pando" as the known organism with the highest living biomass.
The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.
A species ( pl.: species) is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. [1] It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.